1. Field of the Invention
This invention relates to electrical connectors. More particularly, this invention relates to electrical connectors having substantial shielding effectiveness against electromagnetic interference and especially against electromagnetic pulse.
2. Description of the Prior Art
Electrical circuitry often must be protected from disruptions caused by electromagnetic interference (EMI) entering the system. External EMI energy is an undesired conducted or radiated electrical disturbance than can interfere with the operation of electronic equipment. Internal EMI energy is the unwanted noise or unwanted interference generated by electrical or electronic circuitry within a system. The EMI disturbance can occur anywhere in the electromagnetic spectrum. Radio Frequency Interference (RFI) is now used interchangeably with EMI but generally is limited to interference in the radio communication band. Connectors are particularly susceptible to EMI energy because of the numerous contact areas and openings for cable and external electrical contacts. However, the art has developed sophisticated electrical connectors having substantial shielding effectiveness against EMI (often referred to as EMI/RFI) energy. Illustrative prior art connectors of good to superior shielding effectiveness are set out in U.S. Pat. Nos. 3,609,632 and 4,106,839.
With the development of nuclear explosives, another type of electromagnetic radiation was observed. The nuclear explosion, and in some circumstances large scale chemical explosions, produces a sharp pulse (large impulse-type) of radio frequency (long wave length) electromagnetic radiation. The intense electric and magnetic fields created by electromagnetic pulse (EMP) energy can damage unprotected electrical and electronic equipment over a wide area. As a result, a demand has arisen for electrical connectors having substantial shielding effectiveness against EMP and EMI energy threats.